Twist-drill-point-grinding machine



Mar. 20, 1923 H. HUNT ET AL TWIST DRILL POINT GRINDING MACHINE Mar. 20,1923.

H. HUNT ET AL TWIST DRILL POINT GRINDING MACHINE 10 sheets-sheet 2 FiledJune 4 Mar. 20, 1923.

H. HUNT ET AL TWIST DRILL POINT GRINDING MACHINE Filed June 4, 1920 10sheets-sheet 5 Mar. 20, 1923. 1,448,746

H. HUNT ET AL TWIST DRILL POINT GRINDING MACHINE Filed June 4, 1920 10sheets-sheet 4 Mar. 20, 1923.

H. HUNT ET AL TWIST DRILL POINT GRINDING MACHINE Filed June 4, l0sheets-sheet 5 Mar. 20, 1923.

H. HUNT ET AL TWIST DRILL POINT GRINDING MACHINE Filed June 4, 1920 10sheets-sheet 6 Mar. 20, 1923.

H. HUNT ET AL TWIST DRILL POINT GRINDING MACHINE l0 sheeias-sheet '7Filed June 4, 1920 Mar. 20, 1923.

H. HUNT ET AL TWIST DRILL POINT GRINDING MACHINE Filed June 4, 1920 10sheets-sheet 8 lww zo, 1923.

H. HUNT ET AL.

TWIST DRILL POINT GRINDING MACHINE Filed June 4, 1920 10 sheets-sheet 9Wain s Mar. 20, 1923.

'H. IHUNT ET AL TWIST DRILL POINT GRINDING MAGHINE- Filed June 4, 192010 sheets-sheet 10 towards and away from the grinding wheel.

Patented Mar. 20, 1923.

NITED STATES HERBERT HUNT, HERI BERT WILLIAM HUNT, AND PERCY ENGLAND.

PATENT OFFICE.

Runner MANCHESTER,

TWIST-DRILL-POINT-GBINDING MACHINE.

Application filed June 4,

Ireland, and residents of Manchester, England, have invented certain newand useful Improvements in Twist-Drill-Point-Grind- ,ing Machines (forwhich we have filed an application in Great Britain and Ireland, No.4213, dated Mar. 11, 1918), of which the following is a specification.

.This invention has for its objects a construction of machine which willensure the accurate pointing of a twist drill, and (2) a machine whichwill ensure of the cutting edges of the point of the drill having anuniform angle of clearance from apex to circumference of the drillpoint. v

In achieving the first object of the inven tion, the drill, whilst itspoint is being acted upon by the grinding wheel, is supportedcircumferentially near the said point in a close but free fitting bushor sleeve'which serves to centre the drill and act as a steady for thedrill to bear against whilst the point is being ground. The said bush orsleeve by having a portion of its end cut away to form a shoulder also:serves in conjunction with one of the flutes of the drill, to facilitatethe iorrect setting of the drill in relation to the drill holdingspindle.

In achieving the second object of the invention, the drill in additionto having a rotary movement about its own longitudinal axis, and aslight longitudinal movement during each half rotation of the drill, has

an angular movement about a vertical axis .of belt driving pulley andclutch.

near to the end to be pointed, the said vertical axis preferably passingthrough the said sleeve, and the combined movements result-ing (a) inthe drill being accurately pointed and the cutting edges ground, and(7)) in the clearance behind the cutting edges being the same or almostthe same angle near the apex of the drill point as at the periphery,thereby rendering those parts of each gutting edge near the apex asefficient, or almost as eflicient as the parts near the periphery of thedrill point.

A further feature of the invention con sists in obtaining the saidforward movement of the drill twice in each revolution 1920.Seria11qo.386,589.

of the drill by a single cam, or in other words, using one cam for bothlips of the drill point."

Another feature consists in using the periphery of the grinding wheel(instead of one of its side faces) for grinding the drill point, and inmoving the wheel laterally during the grinding operation so as to keepthe periphery of the wheel true and fiat. A

further feature of the invention consists in providing means for varyingthe lateral movement of the grinding wheel, and mov ing the wheel clearof the drill point when requiring to change the drill. Alternatively,the invention'consists in moving the drill bodilyto and fro across theedge of the grinding wheel, the latter in such case being capable ofrotary movement only. Combined with-the improved machine may be anattachment for grinding the flutes of the drill.

In order that the invention shall be more readily understood referencewill now be made to the accompanying drawings, Whereon:

Fig. 1 illustrates a front elevation (in part).

Fig. 2 a left hand elevation (in part) and Fig. 3 a plan (in part) ofthe improved machine.

Figs. 4 and 5 illustrate side and end views respectively of the bush forsupporting the drill near the end to be ground.

Fig.6 illustrates a form of cam used in the machine.

Figs. 7 to 13 illustrate various further detailed parts. hereinafterdescribed.

Fig. 14 illustrates a modified arrangement Fig. 15 illustrates a frontview.

Fig 16 a plan, and x Fig. 17 an end view of a modified construction ofthe improved machine. .In Figs. v1 and 15 the drill 'holdlng mechanismis shown at right angles to the axis of the grinding wheel. I .Fig. 18illustrates a plan view of a modification of Figs. 15, 16 and 17.

. Figs. 19, and 20 are side and plan views respectively of an attachmentused with the improved machine. Referring to Figs. 1 to 14, the machinecomprises a pedestal .1 upon which rests sis sition.

i of

loosely fit the drill to be pointed.

concentric to the stud 7 In the shoulders a hollow stand 2 and tray 3.In one with said tray is a raised guide block 4 whereon is mountediaslide 5, see Figs. 7 and 8, capable of moving to and fro along the guideblock 4. Upon saidslide rests a plate 6, see Figs. 9, 10 and 11. Bothslide and plate are provided .with a hole through which passes a stud 7,see Fig. 3. The stud loosely fits'the hole in the slide, but is heldfirmly in the hole of the plate, so as to turn therewith by a set screw7.

' In one with said plate 6-is a guard 6, parallel sided part of theplate is a parallel sided sinking, see Fig. 10, the edges 6", 6 of whichare bevelled, see'Fig. 11, to form guides for a drill head 8. The slide5 extends below the drill head Sand in the part below the drill head isformed with a curved'slot 9 see Figs. 3 and 7. Extending downwards fromthe plate and passing loosely through the slot 9 in slide 5 areroller-carrying studs 10 whereby the plate 6, whilst free to moveradially about the stud 7 is held to the slide and guided in thepath ofthe slot. In the drill head 8 is mounted the spindle 11, the forward endof the spindle being hollow and fitted with the usual chuck 12 forreceiving and centrally gripping the twist drill requiring to be ground.

In one with-the drill head 8 is a boss 15, see Fig. 2, which forms thebearing of a spindle 14. Upon the upper end of the spindle is keyed abevel pinion 15 and a disc cam 16, see Fig. 6. Keyed upon the rear endof the drill-holding spindle 11 is a further bevel wheel 17,'this latterbeing double the size of, and meshing with the pinion 15. Upon the lowerend of the spindle 14 is keyed a bevel wheel 18. 1

By means of a pair of plungers 19, 19' and springs 20, 20 arrangedwithin holes in the base of the drill head, see Figs. 1, 3 and '13, ahardened steel stud 21 on across-bar 6 on plate 6 is constantly held inyielding contact with the periphery of the disc cam.

Upon or in one with the stud 7 are clamp-1 ing jaws 7*, in which fits abush 7*, a screw 7 clamping the bush when'set to the correct po- Thedrill to be ground projects through the bush, see Fig. 4. The bush atits forwardend is partly cut away to form 7, see Figs. 4 and 5, saidshoulders lying about a sixteenth of the interior diameter of the bushor sleeve above. the longitudinal axis of the sleeve. By means of one ofthe shoulders, and by causing one edge of a flute in the drill to lieflush with the shoulder (the fingers readily feeling when this is done),the drill can be readily set to the correct position relatively to thespindle 1.1, see Fig. 5. The internal diameter the bush or sleeve issuch; as 'to closely bult it 1 each machine will be supplied a set ofinthe other end of'which is within the pulley bearings and pulleys,

'pin44 or 'terchangeable bushes or sleeves, the internal diameters ofwhich will vary with the differ ent diameters of drills to be pointed.

Extending from the boss 13 is an arm 13 which terminates-in a tubularpart 13*. In such part rotatably fits one end of the shaft 22. Upon thesaid shaft is keyed abevel pinion 23 which meshes with the bevel wheel18. Also upon the shaft 22, but at the other side of the tubular part 13is keyed a collar 24, whereby, movement of the boss and arm, is movedendwise. Eccentrically connected at one end to the bevel wheel 18 is alink 25, pivotally connected to an arm 26 branching from the slide 5,see Figs. 1, 3 and 7. With the wheel 18 in motion, the plate 6 is movedto and fro about the pivot 7 Secured to and extending-from the undersideof the tray 3 is a bracket 27, which at its free end supports thebearings 28 of the fast and loose belt pulleys 29, 30, said bearingsbeing held to the bracket by a plain stud 31, and set screw 32, andbeing free to with any lateral the shaft 22 swivel in a horizontal planeabout said stud.

The shaft 22 is free to slide to and file t e fast pulley 29 beingslidably keyed to the shaft. A belt-fork shifting bar 33 is mounted inthe upper ends of the bearings, and a ball and spring (concealed withinone of the bearings) and notches in the bar 33 serve to hold the beltforks in either of two positions. In lieu of then fast and loose beltpulleys and belt fork, a single belt pulley 29 and clutch 29", see Fig.14', may be provided.

At the right-hand end of the machine is arranged the grinding wheel 34.This wheel is carried by a shaft 35 mounted in ball bearings within aslide 36, the ball adjusting type, so as to keep the wheel shaft alwaysin ali ment. Keyed upon-the rear end of the s aft 35 is the belt pulley37. Below the slide 36 is a stud 38 free to swivel about its axis andconnected to such stud is one end of a lever 39. This lever is fulcrumedon a peg 40 fitting ahole in the block 41 cast in one with, or fitted tothe tray 3. Pivotally connected to the lever 39 is a bar 42 having aseries of holes 43 by which the bar may engage a pin 44 on the plate6,the bar terminating in a handle 45 by which it may be lifted clear ofthe lowered on to such pin. means of this bar and lever,

4 By the grind 'ing wheel 34, when the plate 6 is swung to and fro aboutthe stud 7 is caused to move to and fro endwise, i. e., in the directionof the arrows, see Fig. 3. I

When requiring to insert a drill in the chuck 12, the. bar 42 is liftedoff the pin 44, and by pulling the bar forward thewheel bearings beingpreferably of the self-ad- 34 and bearing 36 are moved to the rear ofthe machine. A wheel guard 46 is fixed to and moves with the bearing 36.

An opening 3 in the tray allows the dbris from the drill point and wheelto fall into a pen47 within the stand 2, that part of the plate 6 withinthe guard 6, being sloped 50 as to direct the lubricant and dbris to theopening 3 Upon the side of the slide 5 is secured a lug 5, see Figs. 3and 7 which is screw-threaded internally, and through which screws ascrewed spindle 48. This spindle is rotatably mounted in a. fixed boss49 and is held against endwise movement b a flange 50 and collar 51.Upon said spindle is keyed a ratchet wheel.52 and secured adjustably tothe spindle by nut 48 is a hand-Wheel 53. Pivotally supported on thetray 3 is a lever arm 54, see Fig. 2, which near to its upper endcarries a pawl 55, the free end of the pawl being adapted to engage theteeth of the ratchet wheel 52. Upon this side of the lever arm 54furthest from the ratchetwheel is a projection 54*, which overlies andunder the force of a spring 54 bears against the head of a screw 56screwing into the tray 3. Upon the plate 6, see Fig. 3, is a projection6 which comes directly opposite the lever arm 54, and with the pivotalmovements of the plate 6 in one direction, serves to push against thelever arm 54 and operate the pawl 55 which, in turn, rotates the ratchetwheel a portion of a revolution; With the ratchet wheel thus rotated,the screw 48 is rotated and thereby caused to bodily trayerse the slide5 and with it plate 6, drill head 8, drill spindle 11 and drill pointtowards the grinding wheel, the shaft 22 and pulley bear ings 28allowing of this bybeing free to swivel about the stud 31 and spindle14.

It will now be seen that with the shaft 22 in motion the drill-holdingspindle and drill will be rotated about their own axis. Simultaneouslywith the said rotary movment of the drill the disc cam 16, during eachhalf-revolution of the drill, will impart to the drill a slightlongitudinal movement towards and away from the grinding wheel. Further,owing to the eccentric connection of the link 26 with the bevel wheel18, the plate 6 and the drill-holding spindle and drill will move to andfro in the, arcof a circle, having stud 7 as axis, the combined motions,with the drill point in contact with the grinding wheel and with theaxis of the drill lying at an oblique angle to the peripheryof thegrinding wheel, serving primarily to point the drill, and secondly togrind and impart clearance'to the cutting edges of the drill point, theangle of clearance being the same or practically the same nearthe apexof the drillpoint as near'the periphery. This uniformity of the angle ofclearance is due to giving the drill a pivotal or swinging movementwhilst moving it endwise towards the grinding wheel, and

also to arranging the vertical axis about which the drill movespivotally ashort distance from the end of the drill.

H The shape of the disc cam 16 is shown more clearly in F i 6. Aspreviously stated, the cam is driven t rough gears of two to one ratioand therefore the drill is moved to and fro endwise twice in eachrotation of the allows it to move back during the second half of therotation. Through the gears 15, 17, the drill, in the same period, makesonly half a rotation.

To aid in setting the drill relatively to the drill spindle 11, a shortlatching lever 57 is provided which is pivoted to a lug on the top ofthe drill head 8 and adapted to engage a notch in the collar 58adjustably secured to the spindle 11. After setting the drill spindle,the latch isthrown back and the spindle and drill made free to rotate.The drill is then inserted with one of the flute edges level with theshoulder 7 as previously described. The lateral movement of the grindingwheel will preferably be not less than the full width of the wheel, sothat whilst grinding'the drill the wheel will be kept true and flat.

'Obviously the bush or sleeve '7" may be shouldered at both ends andthus be reversible. There will be a set of bushes or sleeves 7 for arange of sizes of drills, and for each range the bushes or sleeves willpreferably be the same diameter on their exterior, whilst the interiordiameter will vary to suit the drill. For a range of larger or smallersizes of drills, the stud 7 may be changed for a stud having a largeropening for the bushes, or the hole in the stud mav be fitted with aliner, capable of being removed to allow of bushes ,oflarger or smallerdiameter being used.

The hand-wheel 53 may be furnished with a pin 53 designed to lift thepawl 55 clear of the teeth of the ratchet wheel after a pre determinedrotation of the ratchet wheel and a corresponding predetermined traverseof the slide '5. If desired, thescrew 48 may be rotated by hand, andwhile the screw is be ing so rotated, the pawl 55 maybe turned up' outof the way, a spring and plunger 59 holding it in the raised position.

By alte ring the lever 39 from one hole to another the endwise movementof the grinding wheel may be varied.

Referring now to Figs. 15 to 20, the machine therein shown is similar tothat shown in Figs. 1.to 14, but differs chiefly in that the grindingwheel 34 is incapable of endwise movement and the drill is bodily movedto and fro in a direction parallel with the axis of'the grinding wheel.4

Other features of difference are the arrangement of mechanism forimparting angular movement to the drill, and the arrangement of cam forimparting endwise movement tothe drill.

In this modification the tray carries a guide 61 whereon is mounted aslide 62, this latter being movable along the guide by means of a screw63 screwing through a screwed part 64 of the guide 61. In one with theslide 62 is the guide 65 of a further slide 66 adapted to move in adirection at right angles to the slide 62. The pivot stud 67 of theplate 68 is carried by the slide 66, and said slide extends'rearwardlyto support the rearward part of the plate 68, a

roller 69 being provided'for the extension of the slide to rest upon.

Upon the rear end ofthe plate 68 is mounted the drill head 70 in whichis mounted the hollow drill-holding spindle 71, said spindle beingslidably mounted within a tube or bush 72 in the head. Said tube at oneend is formed in one with a boss 73 and near such boss carries a plate74. At its other end the tube is coned and slitted, that part of itsperiphery adjacent to the conical end being screw-threaded and adaptedto receive the screwed art of the boss of the hand wheel 75. yslackening the hand wheel the tube 72 frees the spindle 71 andallows'the latter to be adjusted endwise by the knob-ended pin'76whilst'by tightening the hand wheel the tube 72 and the spindle 71areheld in'the correct positions relatively to the grinding wheel 34.

At its forward end-the twist drill is supported in an interchangeablebush 77 carried by thepivot 67 as in the machine shown in Figs. 1 to 14.

Mounted in the drill head is a lay? shaft 78 whereon is'slidably keyed aspur pinion 79 and a bevel pinion 80, the former meshing with a spurwheel 81 on the tube 72 and the latter meshing with a bevel wheel 82keyed to a vertical .spindle 83 carried in a bearing bracket rising fromthe plate 68, see Fig. 16. Upo-n'saidvertical spindle 83 is also keyedalargerbevel wheel 84 and with suchqwheel meshesa bevel wheel 85. keyedto a short spindle. 86 carried in abracket 87 and furnished with: aclutch. 88 and handle 89, one half the-"clutch and the handle beingmovable as one and the other half of' the clutch being in one with theboss of the bevel wheel 85.

Meshing with the bevel wheel 84 is. a furthenbevel wheel 90 looselymounted on a shaft 91,- the boss of the wheel fitting a bearing 92branching from the bearing bracket of the vertical spindle 83 and beingprovided with-a half-clutch 93 whereby and a complemental half-clutch 94(slidably keyed on the shaft 91) and a lever 95, see Fig. 16, the motionof the shaft 91 may be transmitted to the bevel wheel 90 or whereby thedriving connection may be broken.

The shaft 78 is slidablein the drill head and at one end said shaftisconnected to the plate 74 on the tube 72. At its other end the shaft78 is fitted with a cam 95. Within recesses in the drill head aresprings 96 and telescopically fitting the springs and recesses areplunger-headed pins 97 carried by the plate 74. Upon an extension 68 ofthe plate 68 is a hardened steel pin 68 against which the ,cam 95 bearsunder the pressure of the springs 96.

Secured to the edge of the extension of the slide 66 is-a. bracket 98and connecting the free end of said bracket with an eccentricallyarranged pin on the bevel wheel 84 is a link 99. The shaft 91 receivesits rotary motion from the main shaft 100 through a worm 101 andwormwheel 102 and also through a bevel wheel'103 mounted on verticalspindle 104, see Fig. 17, and a bevel wheel 105 mounted on the shaft 91.

Under the notations of the bevel wheel 84 the plate 68 and with it thehollow spindle 71 and the twist drill are given a to-andfro angularmovement about the pivot stud 67, whilst the hollow spindle 71 and twistdrill are rotated about their own axes, further by means of the cam 95and springs 96 the dull is given an endwise movement towards and awayfrom the grinding wheel twice in each revolution of the drill. With thedrill held at an oblique angle'to the periphery of the grinding wheeland moved as aforesaid, the drill is ground and pointed,

the necessary clearance is imparted to the cutting edges of the drillpoint, and the angle of clearance is practically the same for the wholelength of the cutting edges.

Engaging an eccentrically positioned block 106 on the worm wheel 102 isthe .grooved arm of a bell-crank lever 107 the other arm of such leverbein connected by a link '108 to the slide 66. he lever takes itsfulcrum ,on a bracket 109 branching from the end bearing of the maindriving shaft. By this arrangement the dr ll is moved bodily to and froacross the periphery of the grinding wheel, thus ensuring ofthei' wheelwearing evenly.

As in the machine shown in Fig'. 1, a latch 110 pivoted to the drillhead and adapted to-enter a notch in the boss 73 of the tube 72 servesto'hold the spindle against rotation whilst the twist'drill is beingplaced in the clutch and also serves to position the drill for grinding.V

The setting of the drill spindle 71 to the correct position forreceiving the drill is effected by the handle 89 and clutch 88, thelatter being normally held out of engagement bya spring concealed withinthe clutch but on being engaged serving to rotate the bevel Wheels 85,84 and spur wheels 79, 81.

To enable the slide 66 to take up various positionsrelatively to theguide 65., the link L08'is connected to the slide through the medium ofa rack 111 mounted in a groove below the slide, and engaging such rack1s a toothed wheel mounted. upon a vertical spindle 112 journaled in theslide and at its upper end being fitted with a fixed notched wheel 113"and a swivelling lever 114 carrying a spring-pressed locking pin 115,the lever, when the in is drawn back, allowing of the -rotat1on of thetoothed wheel below the slide and the adjustment of the slide along therack.

Instead of being operated by power, the improved machine shown in Fi s.15 to 17 may be operated by hand, in whlch case the shaft 91, the bevelwheel 90, clutches 93, 94, bevel wheels 103 and 105, worm wheel 102, andworm 101 will be dispensed with, see Fig. 18., In such connection thelever 107, eccentric block 106, and link 108 are also dispensed with,and the adjustment of the wheel 116 and screw 117 as shown in Fig. 18,the screw being rotatably mounted in a bracket or boss 66 on slide 66and the screw engaging a screwed part 65 of the guide 65.

When the machine is hand-operated, the

clutch 88 may be dispensed with, the handle 89 being fixed to the bossof the bevel wheel 85. v

The twist drill may be automatically fed against thegrinding wheel aftereach complete revolution, by mechanism similar to that alreadydescribed.

The flutes of a drill are usually narrower towards the shank end of thedrill and as the point of the drill is ground away in sharpening it isdesirable that the flutes should be maintained ata uniform width. Forthis purpose the improved machine comprises a flute grinding wheel 118,see Figs. 17, 19 and 20 mounted upon an extension of the shaft 100;Further the tray 60 is fitted with an adjustable work. holder, such.holder comprising a non-rotary vertical screw 119 passing through'a'fixed boss 120 with internally screw-threaded bush 121, said bush beingfurnished with a hand-wheel 122 whereby it may be rotated and the screw119 raised or lowered. At its upper end the screw carries a rod or bar123 upon which is adjustably mounted a slide 124. In one with such slideand lying at an angle therewith in plan and elevation is a V-shaped toolcarrier 125 the said slide and carrier being movable to and fro on thebar 123 by meansof a lever 126 pivoted to the carrier and projectingloosely through an opening in the relatively fixed bar 123, see Fig. 20.The drill is laid in the carrier and positioned with its pointed endnext the grinding wheel by means of an adjustable stop block 127.

Upon the nd of the" carrier is a small 2- shaped plate 128, see Fig. 17adapted to act as the gauge for holding the drill in the correctposition for grinding, first one flute and then the other, the smallspurs being preferably made to two sizes to sult different sizes ofdrills.

The angle of the carrier 125 relatively to the liar 123 in plan is suchasto causethe flutes of the drill to be practically parallel 'with thegrinding Wheel 118. slid 66 is effected periodically by a hand- Whatwe'claim is In a twist drill point grinding machine, a verticallydisposed stud, a support for said stud on which it rests solidly whilefree to swivel, said stud near its upper end having a through openingand being slitted vertically to form jaws, a cylindrical interchangeablebush within said opening and'between said jaws, the ends of thebushwhich extend beyond the sides of the stud having radiating shoulderseach lying a' slight distance out of the plane of the longitudinal axisof the bush, the inner diameter of the bush being such as to receive atwist drill and hold same against lateral disturbance in all directionswhilstleaving the. drill free to rotate,

and means for tightening the jaws on to said bush, as herein set forth.

In witness whereof we have hereunto set our hands. r.

HERBERT HUNT. PERCY HUNT. HERBERT HINT.

